放养密度对大杂交鲟生长性能的影响及生理应答机制

摘要

为探讨放养密度对鱼类生长及生理应答机制的影响规律和作用，作者以大规格大杂交鲟(达氏鳇(Huso dauricus)♀×施氏鲟(Acipenserschrenckii)♂)为实验材料，研究了平均初始体质量约为243 g/尾，放养密度分别为6(SD1组)、9(SD2组)、12(SD3组)、15 kg/m3(SD4组)条件下，不同放养密度处理70 d后的实验鱼生长性能变化及生理应答机制。结果显示，放养密度对大杂交鲟肥满度影响不显著， SD2组鱼类具有最大的特定生长率和生长效率，随着放养密度增加，日增质量显著降低(P<0.05)，特定生长率和生长效率下降。测定了血液甲状腺素(T4)、三碘甲腺原氨酸(T3)和皮质醇水平变化，发现放养密度能引起大杂交鲟3个血液生理指标发生显著改变；随着养殖时间推移， T3和皮质醇浓度显著升高， T4浓度显著下降(P<0.05)。这些结果说明神经内分泌活动的变化引起大杂交鲟血液生理指标变化，进而影响实验鱼生长性能。因此，在该养殖条件下推荐的养殖密度为9 kg/m3。%To study the effect of stocking density on growth performance and mechanism of physiological response in hybrid sturgeon, an experiment was performed on large-sized hybrid sturgeon (Husodauricus♀ ×Acipenser schrenckii♂), with an initial weight of 243 g per fish, at a stocking density of 6 (SD1 group), 9 (SD2 group), 12 (SD3 group), and 15 kg/m3 (SD4 group) over a 70-day period. Results showed that daily weight gain decreased sig-nificantly (P<0.05) with increasing stocking density. Moreover, increasing density resulted in a decrease in specific growth rate and growth efficiency, with the best specific growth rate and growth efficiency in the SD2 group. However, density had an indistinguishable effect on relative fatness. In the study, serum thyroxine (T4), triiodothy-ronine (T3), and cortisol were significantly affected by stocking density. T3 and cortisol levels increased signifi-cantly (P<0.05), whereas the T4 level decreased (P<0.05) over breeding time. The results indicate that the change in neuroendocrine activity affect the serum physiological indices, which can influence growth performance in experi-mental fish. Therefore, we suggest that 9 kg/m3 as an appropriate stocking density for aquaculture.